Electromagnetic device



18, 1945- G. M.' sTAPLE'roN 2,391,277

' ELECTROMAGNETI C DEVI C E Filed May 5, 1942 Patented Dec. 18, 1945 ELECTROMAGNETIC DEVICE George M. Stapleton, Sea CliH, N. Y., assignor. to Ward Leonard Electric Company, a corporation of New York Application May 5, 1942, Serial No. 441,761

13 Claims.

This invention relates to electromagnetically operated switches and relays and to other devices electromagnetically operated.

The invention of this application is an improvement in certain features over the invention described and claimed in my pending application Serial No. 446,324, led June 9, 1942, a division of my pending application Serial No. 420,327, iiled November 25, 1941.

The invention relates to the provision of means for preventing improper operation of the device from the effects of mechanical shocks or jars. If the switch is in the closed position this improvement prevents the opening due to shocks and if in the open position prevents the closing due to shocks.

The main object of the invention is to provide simple and compact means for preventing undesired operation of the apparatus from the effects of shocks. Another object is to provide means which will be readily applicable to various forms and types of electromagnetically operated devices. Another object is to provide a common means for preventing the undesired operation of the device when in the attracted position and when in the unattracted position. Other objects and advantages will be understood from the following description and accompanying drawing.

Fig. 1 is a vertical central section of one embodiment of the invention, the lower portion of the figure being a section on the line I-I of Fig. 4; Fig. 2 is a front elevation looking from the left of Fig. 1; Fig. 3 is a top plan View; Fig. 4 is a section on the line 4 4 of Fig. 1; and Fig. 5 is a vertical section showing a modication.

Referring to Figs. 1 and 2, the magnet frame I is shown of U form having fixed to its middle side portion a pair of bolts 2 for securing the device in a vertical position to a support. A plug 3 of magnetic material is screwed into the upper leg of the magnet frame and locked in position by the nut 3a. The plug 3 projects downwardly to some extent within the winding 4. A sheet of insulating material 5 is introduced between the top of the winding and the underside of the top leg of the magnet; and a similar sheet '5a is positioned at the bottom of the winding and is held in place and adjusted in position by screws 6 which project through and are threaded in the lower leg of the magnet frame. A metal sleeve I of non-magnetic material secured to the plug 3 by rivets 'Ia serves as a guide for the magnetic plunger 8 of the magnet which is freely movable through the lower leg of the magnet. The plunger has a central longitudinal circular opening and in the upper portion thereof is iixed a rod 9 of non-magnetic metal which passes upwardly freely through a central opening in the plug 3. A disk I0 of insulating material having an upturned outer edge is xed to the top of the rod 9. This disk has an upwardly projecting central hub Illa; and freely movable on this hub is a metal contact disk I I having a downwardly turned outer edge which is adapted to embrace the upturned edge of the disk I0 when the parts are in their attracted position. The contact disk is preferably made of silver or an alloy of silver. Between the disks I0 and II and enveloping the hub Illa is a light spiral spring I2 which seats at its lower enlarged portion on the disk I0, the smaller upper portion engaging the underside of the contact disk I I. The contact disk and spring are retained in position by a cap or spacer I3 of insulating material, al1 the parts being held in position on the upper end of the rod 9 by a screw I4 which passes downwardly and has a threaded engagement with the upper end of the rod 9.

The stationary contacts are carried by a yblock I5 of insulating material which has a central opening for the passage of the parts just described and which is secured to the top of the upper magnet frame by the screws I5a. There are three stationary contacts angularly spaced from each other apart. Each contact is carried by a support I6 of inverted U form with outward extensions Ilia by which the support is secured to the block I5. The screws IEb project upwardly through the block I5 for engaging the extensions IBa. One extension IBa of each support is provided with an upwardly extending screw and nut Il for serving as connecting means to an external circuit or circuits. A leaf spring I8 of phosphor bronze or other suitable material extends inwardly Ifrom the top of each support I6 and carries at its inner end a contact I9, preferably of silver or silver alloy. Above the outer end of each spring is positioned a metal strip 20 which extends inwardly over the contact I9 for limiting the uppermost position of the contact. rIhe strip 20 is secured at its outer end to the top of the support I6 by rivets which pass through the outer end of the leaf spring I8. The three contacts I9 are positioned above the contact disk I I and are simultaneously engaged thereby when the plunger of the magnet is in its attracted position. A projection Ic extends inwardly from the upper portion of each support IB under the leaf spring for properly positioning the contacts I 9 and for limiting their downward movement.

A cylindrical metal block 2l of non-magnetic material, such as brass, is secured by the upwardly extending screws 2|1fl to the underside of the lower leg of the magnet. This block has a large central opening 2lb for receiving the lower end of the plunger 8 and a smaller central opening 2|c below the plunger. The lower end of the plunger is provided with an outwardly extending flange 8a which seats against the lower central portion of the block 2| when the plunger is in its unattracted position. The flange 8a also serves as a stop to limit the uppermost position of the plunger 8 when in its attracted position fby the flange engaging the underside of ra circular spacing plate 2|d of nonmagnetic metal on the underside of the magnet frame. This limiting position insures the provision of a small air gap between the upper end of the plunger 8 and the plug 3 for determining the'proper drop-out voltage of the relay when in the fully attracted position. Y -As shown particularly in Figs. 1 and 4, there are fourV equally angularly spaced radially ex- -tend11gs10tsiinthe cylindrical piece 2| which are open at the bottom and extend vertically upwardto near the top of the block 2|. In each of these slots is pivotally mounted a locking or latching piece 23 of special form for overcoming improper operation of the device when subjected to severe shocks. This locking piece is in the form of a plate of non-magnetic material of comparatively small vthickness and may be formed from sheet metal. It has an upwardly extending outer portion from the upper end of which inwardly extends a projection 23a having a downwardly sloping upper edge 23h and an undercut lower edge 23o. In the normal position of these plates 23 the projections 23a are out of the path of the flange 8a of the plunger. Each plate is pivoted on across pin 24 which is introduced within the block 2| through crosswise openings 25 drilled through the block. The holding screws 2|a pass through the junctions of these crosswise openingsand serve to keep the pins 2d from displacement `after the parts are assembled. A metal cover plate 26 is secured to the bottom of the'v block 2| by the screws 2|a.

' Below each plate 23 at its outer portion the plate 25 isupwardly indented at 26a a proper amount for determining theV proper normal position of each plate 23. A downward projection 23d from the inner portion of each plate 23 projects into a perforation formed in the plate 26 and strikes against the outer edge of the opening for limiting the inward movement of the upper end of the plate 23. The mass of the portion of the plate 23 which is at the outer side of the pivot 24 is considerably more than the mass of the portion at the inner side of the pivot which causes the plate to normally seat against the projection 26a. Also the distance from the center of gravity of Vthe mass of the plate 23 to the pivot is much shorter than the distance from the pivot to the projection 23a of the plate. This relationship gives an ampliiied movement of the projection 23a compared with the movement of the center of gravity of the mass of the plate about the pivot, The mass of the portion of the plate at the inner side of the pivot is comparatively small.

Although four of the locking plates 23 are shown in the drawing for obtaining a balanced eiect on the plunger, a lesser number could be used if desired; and in some cases only one such plate could be used. Also, the three angularly spaced contacts give a balanced eiect on the contact disk and in some cases Ya fewer or greater number of such contacts could :be used according to circuit controlling requirements. Although the magnet is shown controlling the closing and opening of contacts, the magnet may be used for other purposes.

When the magnet is energized, the plunger 8 is moved to its uppermost position which causes the assembly of parts at the upper end of the rod 9 to be raised and to bring the contact disk in engagement with the contacts i9. After such engagement the plunger 8 continues to move upwardly which results in the compression of the light springV l2 while the contact disk is in engagement with the contacts I9. .The spring |2 has a small rate of increase in force and does not oppose the magnetic attraction with a rapid build-up in force `when the plunger begins to compress the spring at which time the force of magnetic attraction is relatively weak. This permits a rapid upward movement of the plunger and causes the contact disk to engage directly the upper rim of kthe Vdisk Il). The continued further upward movement of the plunger to its nnal position close to the plug 3 gives an increasing strong pressure of the contact disk lil against the contacts I9 and raises the inner ends of the leaf springs 8. This firm yielding contact arrangement by direct pressure of the plunger and contact disk against ythe contacts I9 which are supported by springs having a relativelyv high rate of increase of force in the last portion of their movement secures relatively high yielding contact pressure for withstanding shock without increasing the size of the magnet as the high contact pressure does not build up against vthe magnetic attraction until the plunger is in a position capable of overcoming relatively large forces. Y v

A further aid in overcoming improper action of the device under shocks-is obtained by the locking plates 23. Assuming the parts in the unattracted position shown in Fig. 1, the eect of a downward impact, or the vertical downward component of an impact, may rst be considered. Such an impact moves the device downwardly and the plunger 8 tends to remain stationary giving an upward movement ofthe plunger relatively to the magnet. This might result in closing the switch contacts giving improper operation. However, the shock causes the' plates 23 to turn inwardly on 'their pivots and force the projections 23a into the pathY of the flange 8a of the plunger and thereby prevents the closing of the contacts. There isa certain amount oi relative movement of the plunger within the magnet before the actual closing of the contacts and before the iiange 8a reaches the projections 23a. This gives the projections an opportunity to enterV the path of the flange 8a before the flange reaches them. Also Vby reason'oithe. fact that the center of gravityof each plate 23lis at a shorter distance from its pivot than its projection 23a, the amplified movement of the projections causes them to move inwardlyv quicker than the relative upward movement of the plunger. Theplunger is there-v by locked or latchedrfrom a relative upward movementsufiicient to close the contacts. After the shock the-parts return to their normal position of Fig. 1 by gravity. Y

Upon the occurrence of an upwardA impact, the plunger will be prevented similarly from closing and likewise overcome thereiectY of any vertical upward component of a shock. An upward impact will cause all parts to move ,upwardlyv which might result in-the plunger moving relatively to. the

magnet when the direction of motion of the complete assembly is reversed. In that event the plates 23 would move in the manner already described and prevent the closing of the contacts.

When the plunger is in the attracted position and the contacts closed, the bottom of the ange 8a is a small distance above the plane of the top of the projections 23a. When the device is subjected to a vertical downward impact, or a vertical downward component of a shock, the projections 23a of the plates will move inwardly quickly under the flange 8a in the manner already described and prevent the plunger from opening the contacts. The downward slope of the top edges 23h of the projections results in the plunger tending to force the projections further inwardly when the flange 8a strikes the inner upper tip of the projections, the inner lportions of the projections then being within vertical planes through the axes of the plates. Fig. includes an additional feature of control for additional protection from upward impacts. The parts corresponding to those already described are indicated by the same reference characters. In Fig. 5 an additional mass or weight 21 is provided having the form of a cylinder with an outwardly extending flange or rim 27a at its upper end. This flange normally engages the under surface of an inwardly extending ange or lip 2 le extending inwardly from the inner portion of the block 2l. Each of the plates 23 is provided with an inward extension 23] which passes closely under the flange 21a. A spring 28 is connected at its lower end to the weight 2l and at its upper end to the lower end of the rod 9, although its upper end could be connected directly to the plunger 8. This spring is under tension and always exerts sufficient force to hold the weight against the rim 2id under normal conditions whether the plunger is in the unattracted or attracted position. The weight could be supported yieldably in any desired manner, such as by a compression spring enveloping the weight and engaging the ange 21a at its upper end and engaging the cover plate 26 at its lower end and by providing suiiicient clearance of the spring from the inner portions of the plates 23.

Fig. 5 shows the normal position of the parts when in the attracted position. When in the unattracted position the mode of operation of the parts for preventing the improper closing of the contacts under downward impacts or upward impacts is the same as already described. When in the attracted position the operation is the same as previously described with reference to a downward impact. But when the impact is in an upward direction with the structure of Fig. 5, any relative downward movement of the plunger suiiicient to open the contacts is prevented because the weight 27 would similarly move relatively downward and strike the projections 23j of the plates 23. This would turn the plates on their pivots and move the projections 23a inwardly under the plunger and prevent suiicient movement thereof to open the contacts. The movement of the weight 21 for4 accomplishing this action is slight compared with the required movement of the plunger to open the contacts or to pass by the top of the projections 23a. Also the distance from the axes of the plates to their projections 23a is greater than the distance from these axes to the flange 21a of the weight giving an ampliiied movement of the projections 23a in relation to the movement of the weight. Consequently the projections 23a will enter the path of the plunger before it can pass the projections.

Although a preferred embodiment of the invention has been disclosed various modifications may be made for adaptation to particular requirements without departing from the scope thereof.

i claim:

l. An electromagnet having a movable magnetic elementl and a support, and a locking element separately pivoted on said support and riormally disengaged from said movable element and movable independently of said movable element under shocks for then engaging and restraining movement of said movable element when said movable element is in the unattracted position and also when in the attracted position.

2. An electromagnet having a movable magnetic element and a support, and a locking element separately pivoted on said support and normally disengaged from said movable element and movable independently of said movable element under shocks and having a projecting portion for then engaging said movable element for restraining its movementl when in its unattracted position and for also engaging said movable element for restraining its movement under shocks when in its attracted position.

3. An electromagnet having a movable magnetic element and a support, and a locking element separately pivoted on said support and normally disengaged from said movable element and movable independently of said movable element under shocks and having a projecting portion for then engaging said movable element for restraining its movement when in its unattracted position and for also engaging said movable element for restraining its movement under shocks when in its attracted position, the distance from the center of gravity of said pivoted element to its axis being less than the distance from said prejecting portion to said axis.

fi. An electromagnet having a movable magnetic element and a support, and a vertically extending locking plate separately pivoted on a horizontal axis on said support and normally disengaged from said movable element and movable independently of said movable element under shocks and having 'a projection for then engaging and restraining movement of said movable element from its unattracted position and also from its attracted position.

5. An electromagnet having a vertically movable magnetic elementA and a support extending below the magnet, and a vertically extending locking plate separately pivoted on a horizontal axis on said support and normally disengaged from said movable element and movable independently of said movable element under shocks and having an upwardly and inwardly extending projection for then engaging and restraining the movement of said movable element when said element is in its unattracted position and also when in its attracted position.

6. An electromagnet having a vertically movable magnetic element and a support extending below the magnet, and a vertically extending locking plate separately pivoted on a horizontal axis on said support and normally disengaged from said movable element and movable independently of said movable element under shocks and having an upwardly and inwardly extending projection therefrom for then engaging and restraining the movement of said movable element when said element is in its unattracted position and also when in its attracted position, the distance from the center of gravity of. said plate to its axis being less than the distance from said projection to said axis.

1 7. An electromagnet having a vertically movable magnetic element and 'a' support extending below the magnet, and a plurality of vertically extending locking plates separately pivoted on said support and normally disengaged from said movable element and movable independently of said movable element under shocks and angularly spaced about a central vertical axis, each of said plates having an upward and inward extension therefrom for 1 engaging and restraining said movable element from movement under shocks whenin the unattracted position and also when in the attracted position.

V8. An electromagnet having a vertically movable magnetic element and a support below the able magnetic element and a support below the magnet,'a movable locking element separately movable on said support and normally disengaged from said movable element and movable independently of said movable element under shocks for then engaging and restraining said element from movement under shocks, and a separately movable yieldably supported Weighted element for engaging said locking element under shocks and for then actuating said locking element to engage said movable element and restrain the movement thereof.

l0. An electromagnet having a vertically movable magnetic element and a support below the magnet, a weighted element yieldably supported in its normal upper position, and a separately pivoted locking element on said support and no1'- mally disengaged from said movable element and movable independently of said movable element under shocks and having a projection for then restraining movement of said movable element and having a second projection engaged by said weighted element under shocks for actuating said locking element to then engage and restrain said movable element when said weighted element moves from its normal position to engage said second named projection.

11. A shock proof device having a normally stationary member, a reciprocating plunger movable back and forth with respect to said member in a substantially straight line between two positions, and a locking element biased to inoperative position and automatically operable against its bias in response to the application of shock to said device to lock said plunger in either of said positions.

l2. A shock proof device having a normally stationary member, a reciprocating plunger movable back and forth with respect to said member in a substantially straight line between two positions, and a locking element biased to inoperative position and automatically operable against its bias in response to the application of shock to said device to engage said plunger for preventing movement of said plunger out of the position to which it has been moved.

13. A shock proof device having a normally stationary member, a reciprocating plunger movable back and forth with respect to said member in a substantially straight line between two positions, and a locking element biased to inopshock to said device to lock said plunger in each Y of said positions. Y

GEORGE M. STAPLE'ION. 

